When a woman is intoxicated, she is less likely to have control over who she is attracted to. As such, under the influence of alcohol, she is attracted to many more guys than normal. Thus, she has a magnetic vagina.
Friend #1: Dude check out that girl over there! She's been over every guy here!
Friend #2: Ah, indeed my friend I see her. Normally she's a very respectable girl, but when she's drunk she has a magnetic vagina.